1. Field of the Invention
The present invention relates to a method of forming a photomask, and more particularly to a method of forming a photomask based on a decomposition algorithm of a fin array.
2. Description of the Prior Art
With increasing miniaturization of semiconductor devices, it is crucial to maintain the efficiency of miniaturized semiconductor devices in the industry. However, as the size of the field effect transistors (FETs) is continuously shrunk, the development of the planar FETs faces more limitations in the fabricating process thereof. On the other hand, non-planar FETs, such as the fin field effect transistor (FinFET) have three-dimensional structure, not only capable of increasing the contact to the gate but also improving the controlling of the channel region, such that the non-planar FETs have replaced the planar FETs and become the mainstream of the development.
In current techniques, in order to meet the sub-lithographic requirements, a regular photolithography and an etching process are provided to form fin structures in the FinFET. Additionally, the fabrication of semiconductor device also utilizes a pattern transfer technique, such as the sidewall image transfer (SIT) process, to form required fin structures. However, although being beneficial to fabricate the fin structures in finer critical dimension (CD), the pattern transfer technique also complicates the fabrication process of FinFET. Furthermore, the current fabrication process also faces more limitations, such as fin collapse and malposition issues, so that the current fabrication process still not fully meet the demand of the product, and requires further improvement.